System and method for characterizing macro-grating test patterns in advanced lithography and etch processes

ABSTRACT

The invention teaches a method and system for an accurate profile characterization of test patterns that may be implemented for real time use in a fabrication line. One embodiment is a non-destructive method for acquiring the profile data of the test pattern lines through the use of spectrum data measured with an optical metrology device and a profile library. The profile data comprise critical dimensions of all the test pattern lines included in the set of parameters to create the profile library. The test pattern lines may be designed to evaluate the effectiveness of measures to correct optical proximity, micro-loading or other process effects.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application relates to co-pending U.S. patent applicationSer. No. 09-7275370, entitled “System and Method for Real-Time LibraryGeneration of Grating Profiles” by Jakatdar, et al., filed on Nov. 28,2000, owned by the assignee of this application and incorporated hereinby reference.

BACKGROUND OF INVENTION

[0002] 1. Field of Invention

[0003] Invention relates to the field of process metrology insemiconductor manufacturing and more particularly to the pattern processcharacterization in advanced lithography and etch technology.

[0004] 2. Description of Related Art The semiconductor industry is facedwith the increased need to make features with smaller criticaldimensions. To address this need, lithography processes had to beextended with techniques such as optical proximity correction, phaseshifting, scattering bars, and off-axis illumination, allowing theindustry to extend the life of deep ultraviolet lithography beyond thesub-wavelength barrier.

[0005] In advanced lithography, the effect of optical proximity ispronounced and very significant. Optical proximity effect manifestsitself in the features where the line ends become short or longdepending on whether it is positive or negative resist is used, linewidths increase or decrease based on local density patterns, comers arerounded instead of being at right angles. Some of the factors causingthe optical proximity effect are optical factors such as theinterference of light beams transmitted through adjacent patterns,variation in the resist processes influenced by the quality of theresist, bake temperature and length of wafer baking, and resistdevelopment time, reflection from the substrate, and irregularities ofthe substrate. Optical proximity correction (OPC) is the set ofcorrective measures used in lithography to compensate for the presenceor absence of adjacent features. For example, for structure lines thatbecome shorter and rounded, OPC measures may include lengthening theline and or using enlargements at the ends such as hammerheads andserifs. Alternatively, different parts of the pattern may be widened ornarrowed to compensate for the projected optical proximity effect.

[0006] Micro loading effect is caused by the etching rate varying in achip or wafer depending on the density of the pattern components. Anarea or segment of a pattern may be over-etched or under-etched based onnumber and type of nearby pattern components. Dummy patterns are used tocompensate for the micro loading effect.

[0007] Phase shift mask is an advanced lithography process of shiftingthe intensity profile of the light for the purpose of controlling thefocus settings so as to create an asymmetrical displacement of thephotoresist pattern. The mask may employ multiple degrees of phaseshifting across the mask depending on the pattern to be formed. The typeof resist, the difference in the multiple phases of the light on eachside of the light shielding pattern, the focus and length of lightexposure may all be controlled collectively to provide the desiredpatterning results.

[0008] Test patterns are used to characterize optical proximity, microloading, and other process effects. For example, the five-finger-barpattern is commonly used to determine the process effect and correctiveeffect of a pattern design. Whether it is the use of OPC measures, dummypatterns to compensate for the micro loading effect, or the use of phaseshift masks, there is a need for metrology methods to get a moretwo-dimensional or three-dimensional profile of the grating features ofthe test pattern in order to evaluate the effect of these correctivemeasures. Although there are numerous non-destructive techniques forlinewidth measurements, such as the scanning electron microscope (SEM)and optical microscope, none of these methods can provide completeprofile information. Cross-sectional profile metrology tools, such asthe atomic force microscope (AFM) and the transmission electronmicroscope that provide profile information are either too slow and ordestructive; thus, these metrology devices are not implemented for inline/in situ applications.

[0009] Two optical metrology equipment setups may be used in opticalprofile metrology to measure test patterns in a non-destructive manner:those of spectroscopic reflectometry and spectroscopic ellipsometry. Inspectroscopic reflectometry, the reflected light intensities aremeasured in a broadband wavelength range. In most setups, nonpolarizedlight is used at normal incidence. The biggest advantage ofspectroscopic reflectometry is its simplicity and low cost.

[0010] In reflectometry, only light intensities are measured. R=|r|₂ isthe relation between the reflectance R and the complex reflectioncoefficient r.

[0011] In spectroscopic ellipsometry, the component waves of theincident light, which are linearly polarized with the electric fieldvibrating parallel (p or TM) or perpendicular (s or TE) to the plane ofincidence, behave differently upon reflection. The component wavesexperience different amplitude attenuations and different absolute phaseshifts upon reflection; hence, the state of polarization is changed.Ellipsometry refers to the measurement of the state of polarizationbefore and after reflection for the purpose of studying the propertiesof the reflecting boundary. The measurement is usually expressed as:$\rho = {{\tan \quad \Psi \quad {\exp ( {j\quad \Delta} )}} = \frac{r_{p}}{r_{s}}}$

[0012] Where r_(p) and r_(s) are the complex reflection coefficient forTM and TE waves. Ellipsometry derives its sensitivity from the fact thatthe polarization-altering properties of the reflecting boundary aremodified significantly even when ultra-thin films are present.Consequently, ellipsometry has become a major means of characterizingthin films.

[0013] The advantage of ellipsometry over reflectometry is its accuracy.First, ellipsometry measures the polarization state of light by lookingat the ratio of values rather than the absolute intensity of thereflected light. Second, ellipsometry can gather the phase informationin addition to reflectivity information. Phase information provides moresensitivity to the thin-film variation. Regardless of the techniqueused, there is a need for a non-destructive, high throughput accurateprofile extraction tool for test patterns that can implemented real-timein a fabrication line.

SUMMARY OF INVENTION

[0014] Invention resides in a method and system for an accurate profilecharacterization of test patterns that can be implemented for real-timeuse in a fabrication line.

[0015] One embodiment of the present invention is a non-destructivemethod for acquiring the profile data of test pattern lines in amacro-grating test pattern, the method comprising fabricating a set oftest patterns in a wafer, obtaining spectrum data from the set of testpatterns using an optical metrology device, and accessing the profiledata associated with the closest matching calculated spectrum data in amacro-grating profile library. The set of test patterns in themacro-grating test pattern comprises a number of clustered test patternlines and a number of isolated test pattern lines. The set of testpatterns in the wafer may be designed to evaluate the optical proximity,micro-loading, and other process effects.

[0016] In one embodiment, the optical metrology device comprises anellipsometer or a reflectometer. Some applications of the presentinvention include obtaining of the spectrum data and accessing theprofile data in real-time at the fabrication site. The profile datacomprises detailed geometric information of each sub-feature of themacro-grating, such as width of test pattern lines, distances betweentest pattern lines, and or height of the features in the macro-gratingtest pattern.

[0017] The present invention also includes a system for acquiring theprofile data of test pattern lines of a macro-grating test patterncomprising a macro-grating profile library generator for generating amacro-grating profile library comprising profile data and calculatedspectrum data, an optical metrology device for measuring spectrum datafrom the macro-grating test pattern, and a profiler application server.The profiler application server compares the calculated spectrum data tothe measured spectrum data from the optical metrology device, obtainsthe closest matching calculated spectrum data in a macro-grating profilelibrary instance compared to the measured spectrum data, and accessesthe associated profile data in the macro-grating profile libraryinstance.

BRIEF DESCRIPTION OF DRAWINGS

[0018]FIG. 1A is cross-sectional view of the prior art five-finger-bartest pattern.

[0019]FIG. 1B is a cross-sectional view of the grating feature profileshowing the optical proximity effect for the five-finger-bar testpattern.

[0020]FIG. 2A is a cross-sectional view of a grating profile modelingwith a trapezoidal feature profile with top rounding and bottom footing.

[0021]FIG. 2B is a table listing the critical dimensions of trapezoidalfeature with a top rounding and bottom footing profile.

[0022]FIG. 3 is a top view of a macro-grating test pattern showing arepeating traditional five-finger-bar test pattern.

[0023]FIG. 4 is a top view of a macro-grating test pattern showing arepeating set of cluster and isolated test pattern lines.

[0024]FIG. 5A is a cross-sectional view of a macro-grating test patternshowing a configuration of three-line test pattern, a space, followed byanother three-line test pattern.

[0025]FIG. 5B is a table of values of the variables used in a simulationof the reflected spectra from the test pattern in FIG. 5A.

[0026]FIG. 5C and 5D illustrate ellipsometric graphs of the calculatedreflected spectrum data corresponding to the three sets of dimensionvariable values in FIG. 5B.

[0027]FIG. 6A is a cross-sectional view illustrating a macro-gratingtest pattern with a cluster of test pattern lines, an isolated testpattern line, and another cluster of test pattern lines.

[0028]FIG. 6B is a table of values of the variable used in a simulationof the reflected spectra from the test pattern in FIG. 6A.

[0029]FIG. 6C illustrate reflectometric graphs of the calculatedreflected spectrum data corresponding to the three sets of values forthe variable width of an isolated test pattern.

[0030]FIG. 7 is flow chart of operational steps of acquiring themacro-grating feature dimensions from the measured spectrum data in oneembodiment of the present invention.

[0031]FIG. 8 is an architectural chart of a system for characterizingmacro-grating test patterns in one embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

[0032]FIG. 1A is cross-sectional view of the prior art five-finger-bartest pattern. Traditional simple test pattern structures in masks likethe five-finger-bar test pattern is used to measure the opticalproximity effect on profile dimensions. The features or lines areclassified according to the density or presence of neighboring lines,e.g., dense lines with many neighboring lines, isolated lines, andin-between lines with some neighboring lines. In FIG. 1A, the middleline 3 may classified as a dense line and the two lines on either sideof the middle line, 1, 2, 4, and 5, would be in-between lines.

[0033]FIG. 1B is a cross-sectional view of the feature profile showingthe optical proximity effect for the five-finger-bar test pattern.Features resulting from the five-finger-bar test pattern mask would havedifferent profiles depending on the proximity and density of otherfeatures. For example, the center feature 8 has a bigger height andbottom width than the features at the edge of the test pattern, 6 and 8.Optical proximity corrections in the mask and tweaking of otherfabrication variables are needed in order to make all the features comecloser to the acceptable range of feature dimension.

[0034] To model different test pattern profiles, the features arecharacterized with more dimensions than just the height and width. FIG.2A is a cross-sectional view of test pattern features with a trapezoidalprofile shape that includes top rounding and bottom footing. FIG. 2B isthe associated feature dimensions comprising: the feature footing bottomwidth w1, the trapezoidal bottom width w2, the rounding top width w3,the trapezoidal top width w3, and the rounding top width w4, the bottomfoot height p1, the height prior to the top rounding p2, and totalheight h. Two key dimensional statistics for the trapezoidal featurewith top rounding and bottom footing are percent height bottom foot,calculated with the formula: (p1/h)*100; and percent height of toprounding, calculated with the formula: (p2/h)*100.

[0035] Some applications may include other profile measurements toaccount for T-topping, rounding, undercut, concave sidewalls, convexsidewalls, and the underlying thickness whereas other applications usemuch simpler feature profile dimensions. For the purpose of illustratingthe principles of the current invention, only feature top width anddistances between neighboring features will be considered in themathematical models discussed below. However, the principles andconcepts of the current invention apply to complex feature profilecharacterization.

[0036]FIG. 3 is a top view of a macro-grating test pattern showing arepeating five-finger-bar test pattern. Macro-grating is the termapplied to a test pattern where various combinations of a cluster oftest pattern lines and an isolated test pattern line is repeated in amask. A five-line test pattern 12 is repeated several times as shown inFIG. 3 with two other five-line test patterns 14 and 16. The repetitionof the test pattern line set is key to determining the optical proximityeffect and the outcome of optical proximity corrections in a testpattern.

[0037]FIG. 4 is a top view of a macro-grating test pattern showing arepeating set of cluster and isolated test pattern lines. A cluster ofthree pattern lines 20 separated by some distance from an isolated testpattern line 22 forms a set which is repeated several times asillustrated with another adjacent set consisting of a similar three-linetest pattern 24 separated by some distance from an isolated test patternline 26.

[0038] One of the objectives of the present invention is a method and asystem for getting a more two-dimensional or three-dimensional profileof the grating features of the test pattern in order to evaluate theeffect of the use of OPC measures, dummy patterns to compensate for themicro loading effect or the use of phase shift masks. The remainingfigures will illustrate the method and the system to use calculatedspectrum data to extract the profile dimensions of severalconfigurations of macro-grating test patterns in order to evaluate theeffect of corrective measures in designing masks and in gratingfabrication processes. The purpose of FIG. 5A, 5B, and 5C is toillustrate that the profile dimensions of individual features in amacro-grating test pattern can be determined by an ellipsometricmetrology device and a spectrum data matching process. FIG. 6A and 6Billustrate a similar process where the individual features in adifferent macro-grating test pattern can be determined by areflectometric device and a similar spectrum to data matching process.Ellipsometric, reflectometric or other optical metrology devices may beused. FIG. 7 and 8 illustrate the method and system where a profilelibrary containing calculated spectrum data is matched against themeasured macro-grating test pattern spectrum data to get themacro-grating feature dimensions.

[0039]FIG. 5A is a cross-sectional view of a macro-grating test patternshowing a configuration of a cluster of three test pattern lines, aspace, followed by another cluster of three test pattern lines. In thefirst cluster of test pattern lines, the middle test pattern line 32 hasa line width represented by the variable L0, the distance between themiddle test pattern line 32 and the next pattern line 33 is representedby a variable L1, and the width of the next test pattern line 33 isvariable L2. L3 is the variable distance between test pattern line 33 ofthe first cluster and test pattern line 34 of the second cluster. FIG.5B is a table of values of the variables used in a calculation of thereflected spectra from the test pattern in FIG. 5A. Three sets of valuesin nanometers (nm) were selected for the variables L0, L1, L2, and L3 ofthe macro-grating test pattern in FIG. 5A.

[0040]FIG. 5C and 5D illustrate ellipsometric graphs of the calculatedreflected spectrum data corresponding to the three sets of dimensionvariable values. The X axis in FIG. 5C is the wavelength in nanometersand the Y axis shows tan (Ψ). As can be seen in the graphs in FIG. 5C,the three graphs of tan (Ψ) as a function of the wavelength of thediffracted beam are distinguishable from each other. Since the threegraphs are distinguishable from each other, the calculated spectrum datacan be matched against the measured spectrum data from the macro-gratingtest patterns, thereby providing a technique to get profile data of theentire test pattern. FIG. 5D has the wavelength in nanometers in the Xaxis and the COS (Δ) in the Y axis. Again, as can be seen in the graphs,the three graphs COS (Δ) as a function of the wavelength of thediffracted beam are distinguishable from each other.

[0041]FIG. 6A is a cross-sectional view illustrating a macro-gratingtest pattern with a cluster of test pattern lines, an isolated testpattern line, and another cluster of test pattern lines with the threegroups of lines separated by space. In the first cluster of test patternlines, the middle test pattern line 41 has a constant line width of 150nm, the distance between the middle test pattern line 41 and the nextpattern line 42 is a constant value of 150 nm, the width of the nexttest pattern line 43 is a constant line width of 150 nm, the distancebetween the first cluster of test pattern lines and second cluster oftest pattern lines is 1,650 nm. L represents the variable width of theisolated test pattern line 43.

[0042]FIG. 6B is a table of values for the variable width L of theisolated test pattern line 43. FIG. 6C illustrates reflectometric graphsof the calculated reflected spectrum data corresponding to the threesets of values for the variable width L of the isolated test patternline 43. The graphs have the wavelength in nanometers in the X axis andthe reflectance R in the Y axis. As can be seen in the graphs of FIG.6C, the three graphs of reflectance R as a function of the wavelengthare distinguishable from each other.

[0043]FIG. 7 is flow chart of operational steps of characterizing themacro-grating feature dimensions from the measured spectrum data in oneembodiment of the present invention. Initially, the design for themacro-grating test pattern is developed 200. The design and placement ofthe macro-grating test pattern lines depends on the type of gratingprocess effect being measured. Next, a profile library is generated forthe macro-grating test patterns 210, based on a set of parameters andthe resolution for each parameter. The details of the profile librarygeneration is described in the co-pending U.S. patent application Ser.No. 09-727530, entitled “System and Method for Real-Time LibraryGeneration of Grating Profiles” by Jakatdar, et al., filed on Nov. 28,2000, owned by the assignee of this application and incorporated hereinby reference.

[0044] For example, the macro-grating test pattern is similar to theillustration in FIG. 5A, the variables L0, L1, L2, and L3 may be theparameters that can be varied according to the resolution, measured innanometers, that is desired for the library. The number of parametersselected may include more feature dimensions such as those dimensionslisted for a trapezoidal feature with top rounding and bottom footingprofile illustrated in FIG. 2B. The major consideration is the length oftime and computer resources needed to calculate the spectrum data usingthe rigorous mathematical model in generating the profile library.

[0045] Next, a wafer with the macro-grating test pattern is fabricated220. The macro-grating test pattern may be fabricated in a referencesample or fabricated in test area separate from the production areas ofa wafer. The macro-grating test pattern in the wafer is measured with anoptical metrology device to get the spectrum data 230. The spectrum dataobtained is compared to the calculated spectrum data in themacro-grating profile library 240 and the closest matching instance inthe profile library is selected and the corresponding profile dataaccessed 250. The profile data comprise dimensions of the features ofthe macro-grating test pattern lines including the width, height, andother profile dimensions of each feature in the test pattern. Forexample, if the macro-grating test pattern measured is similar to oneillustrated in FIG. 5A, then the profile data obtained in this stepwould be the values of L0, L1, L2, and L3 in nanometers. If themacro-grating profile library model included the height of the features32 and 34 as well, then this step would provide the height, innanometers, of features 32 and 34. As mentioned above, the macro-gratingprofile library model can include as many critical dimension variablesand the process would provide the value of those critical dimensionvariables from the closest matching profile library instance. Theprofile data obtained in this step is presented 260 in a display and orstored for later use. In addition, the profile data may be compared withan acceptable range established for the fabrication run and an alertcreated if the profile data is outside the acceptable range. The samedata may also be used to fine-tune the macro-grating test pattern designand or adjust a wafer fabrication environmental condition.

[0046]FIG. 8 is an architectural chart of a system for characterizingmacro-grating test patterns in one embodiment of the present invention.Initially, the macro-grating test pattern mask designer 50 is used todevelop the mask needed to compensate for optical proximity effect,micro-loading effect, or other process effect. The macro-grating mask isused in the test pattern wafer fabricator 52 to produce a wafercontaining the macro-grating test pattern. In addition to the testpattern region, the wafer may contain production chips in the productregion. In a concurrent process, dimension data associated with themacro-grating test pattern mask is used as parameters to create aprofile library using the profile library generator 54. As mentionedabove, the process of specifying the parameters and resolution of theparameters for creating the macro-grating profile library 60 iscontained in the co-pending U.S. patent application Ser. No. 09-727530,entitled “System and Method for Real-Time Library Generation of GratingProfiles” by Jakatdar, et al., filed on Nov. 28, 2000, owned by theassignee of this application and incorporated herein by reference.

[0047] The macro-grating test pattern 58 is measured in an opticalmetrology device 57 comprising a metrology illuminator 56 projecting theincident beam and a metrology analyzer 62 processing the diffractedbeam. The spectrum data obtained by the optical metrology device 57 istransmitted to the profiler application server 64. The profilerapplication server 64 uses the macro-grating profile library 60 toselect the calculated spectrum data that is the “closest match” to themeasured spectrum data of the macro-grating test pattern 58 obtainedfrom the optical metrology device 57. The process of obtaining theclosest matching instance of the macro-grating profile library 60 usingthe profiler application server 64 is contained in the co-pending U.S.patent application Ser. No. 09-727530, entitled “System and Method forReal-Time Library Generation of Grating Profiles” by Jakatdar, et al.,filed on Nov. 28, 2000, owned by the assignee of this application andincorporated herein by reference. The profile data associated with theclosest matching instance of the macro-grating profile library 60 isaccessed and stored in a file 66 for immediate or batch processing. Theprofile data comprising width, height, and other profile dimensions ofspecific features in the cluster or isolated test pattern line in themacro-grating test pattern may be compared to acceptable rangesestablished for the fabrication run. An alert is created and displayedin display device 68 if the profile data is outside an acceptable range.The same profile data may also be used to fine-tune the macro-gratingtest pattern design in the macro-grating test pattern mask designer 50and or used to adjust a wafer fabrication environmental condition.

[0048] Measurement of the macro-grating test pattern with the opticalmetrology device 57 may be done real-time and the measured spectrum dataimmediately processed or collected for later batch processing. Theprocess of obtaining profile data 66 for the macro-grating test pattern58 may be done real-time/in situ with a macro-grating profile librarygenerated previously at the beginning of the fabrication run. Theprofile data 66 may be used to automatically adjust wafer fabricationenvironmental factors in an automated wafer fabrication facility.

[0049] The benefit of the present invention is that the method andsystem in non-destructive and can be deployed real-time/in situ toprovide profile data on macro-grating test patterns. The presentinvention also enables the characterization of profile data for all thetest pattern lines included in the model to create the profile library.Although relatively straightforward feature dimensions were used in thefigures and illustrations, more detailed feature dimensions, suchtrapezoidal features with top rounding and bottom footing, may beincluded in the profile library generation step. The principles andmethod of the present invention would still apply for as long as thecalculated spectrum data of a set of test patterns are distinguishablefrom each other.

[0050] In addition to ellipsometers and reflectometers, other opticalmetrology devices may be used and the principles and methods of thepresent invention still apply. Examples of other optical metrologydevices are single wavelength variable incident angle optical metrologydevices, any combination of single wavelength variable incident angleoptical metrology devices and multiple wavelength fixed incident angleoptical metrology devices, and multiple wavelength multiple incidentangle optical metrology devices.

[0051] Foregoing described embodiments of the invention are provided asillustrations and descriptions. They are not intended to limit theinvention to precise form described. In particular, it is contemplatedthat functional implementation of invention described herein may beimplemented equivalently in hardware, software, firmware, and/or otheravailable functional components or building blocks.

[0052] Other variations and embodiments are possible in light of aboveteachings, and it is thus intended that the scope of invention not belimited by this Detailed Description, but rather by Claims following.

What is claimed is:
 1. A non-destructive method for acquiring theprofile data of test pattern lines in a macro-grating test pattern, themethod comprising: fabricating a set of test patterns in a wafer;obtaining spectrum data from the set of test patterns using an opticalmetrology device; and accessing the profile data associated with theclosest matching calculated spectrum data in a macro-grating profilelibrary.
 2. The macro-grating test pattern profile data acquisitionmethod of claim 1, wherein the set of test patterns in the wafercomprises a number of clustered test pattern lines and a number ofisolated test pattern lines.
 3. The macro-grating test pattern profiledata acquisition method of claim 1, wherein the set of test patterns inthe wafer is designed to evaluate the effectiveness of correctivemeasures to compensate for optical proximity and micro-loading effects.4. The macro-grating test pattern profile data acquisition method ofclaim 1, wherein the optical metrology device comprises an ellipsometer,a reflectometer, a single wavelength variable incident angle opticalmetrology device, any combination of a single wavelength variableincident angle optical metrology device and a multiple wavelength fixedincident angle optical metrology device, and a multiple wavelengthmultiple incident angle optical metrology device.
 5. The macro-gratingtest pattern profile data acquisition method of claim 1, wherein theobtaining of the spectrum data and the accessing the profile data aredone real-time at the fabrication line.
 6. The macro-grating testpattern profile data acquisition method of claim 1, wherein the profiledata comprises width of test pattern lines and distances between testpattern lines.
 7. A system for acquiring the profile data of testpattern lines of a macro-grating test pattern comprising: a profilelibrary generator for generating a macro-grating profile librarycomprising profile data and calculated spectrum data; an opticalmetrology device for measuring spectrum data from the macro-grating testpattern; a profiler application server for comparing the calculatedspectrum data to the measured spectrum data from the optical metrologydevice; wherein the profiler application server selects the closestmatching calculated spectrum data in a macro-grating profile libraryinstance, subsequently accessing the associated profile data in themacro-grating profile library instance.
 8. The macro-grating testpattern profile data acquisition system of claim 7, wherein the opticalmetrology device comprises an ellipsometer, a reflectometer, a singlewavelength variable incident angle optical metrology device, anycombination of a single wavelength variable incident angle opticalmetrology device and a multiple wavelength fixed incident angle opticalmetrology device, and a multiple wavelength multiple incident angleoptical metrology device.
 9. The macro-grating test pattern profile dataacquisition system of claim 7 further comprising a macro-grating testpattern mask designer for designing a test pattern comprising a numberof clustered test pattern lines and a number of isolated test patternlines.
 10. The macro-grating test pattern profile data acquisitionsystem of claim 7, wherein the profile data associated with the closestmatching macro-grating profile library instance comprises width of testpattern lines and distances between test pattern lines.
 11. Themacro-grating test pattern profile data acquisition system of claim 7,wherein an optical metrology device measuring the spectrum data from themacro-grating test pattern and the profiler application server operatein real-time mode at the fabrication line.